The aim of the proposed research is to investigate the communication behavior of school-age deaf children and to evaluate their development of communication skills. The studies are designed to shed light on the nature of the language deficit that typically accompanies deafness and on the developmental lag often shown by deaf children in their development of language and communication skills. Training studies are proposed which make use of referential communication tasks as a training context. Both receptive and expressive skills will receive attention. The extent to which deaf children's deficiencies in communication are a result of environmental deprivation will be clarified by comparing their response to training with normal and deficient controls. Structural features of American Sign Language will be identified so that their acquisition can be studied developmentally.